JPS62290163A - Semiconductor device - Google Patents

Abstract

PURPOSE:To prevent a metallic bottom plate of a container from being deformed or distorted when it is contacted under a pressure from springs, to prevent a thyristor from increasing its forward voltage drop or increasing its saturated voltage due to local concentration of large current and to obtain a highquality semiconductor device with a high yield, by embedding a metal plate having high hardness and good heat conductivity in the metallic bottom plate. CONSTITUTION:In a semiconductor device comprising semiconductor element structures 33a and 33b carried on a metallic bottom plate 51 of a container with an insulator 32 interposed therebetween and forced by spring structures 44a and 44b to be contacted with current conducting members 43a and 43b consisting of electrodes 34a, 34b, 35a and 35b having current contact terminals 34at, 34bt, 35at and 35bt, a metal plate 50 having a hardness not lower than that of molybdenum is embedded within the metallic bottom plate 51. The metal plate 50 may be of a hard metal having good heat conductivity such as molybdenum or tungsten. According to this arrangement, the container can be prevented from being distorted or deformed by pressure from the springs or the like. Other pressurized members are also prevented from being deformed. As a result, uniform pressure contact can be obtained constantly.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Object of the Invention] (Field of Industrial Application) The present invention relates to a semiconductor device consisting of high power elements such as transistors and thyristors, and particularly relates to a pressure contact type semiconductor device. This relates to the structure of the bottom of the module container (package).

(Prior Art) A conventional example (Japanese Unexamined Patent Publication No. 57-15452
(No.) will be explained based on FIG.

In the figure, 1 is a first semiconductor element structure consisting of a power transistor 11 and a diode 12, -? - is a second semiconductor element structure also consisting of a power transistor 13 and a diode 14.

These first and second semiconductor element structures are bonded to a common metal bottom plate 17 via insulating substrates 15 and 16, respectively, and the collector electrode terminal 19 of the first semiconductor cable structure 1 is placed above the common package 18. A second semiconductor element structure connected to the emitter electrode terminal 20 on the first semiconductor element structure, ?
-Collector electrode terminal 21 and second semiconductor element structure-
? - emic electrode terminal 22 is led out. A transistor module having such a configuration is easy to assemble into an electrical device, requires less space during assembly, and can achieve a lighter weight.

However, this transistor module had the following drawbacks. That is, since the connection from the emitter electrode or collector electrode is taken out by bonding or soldering, in the case of large current transistors, for example, 100 A or more, bonding or soldering () is not recommended from the viewpoint of thermal distortion, thermal fatigue, etc. It is difficult to increase the size. Furthermore, if there is a breakdown due to overcurrent at a bonding point or the like, there is a risk of a type of explosion in which molten silicone or the like is spewed out of the envelope.

Next, we will discuss the pressure-contact type semiconductor module (Japanese Patent Application Laid-Open No. 60-74462) developed to solve this problem.
This will be explained with reference to the figures. Although FIG. 2 is a plan view of the semiconductor device of the present invention, other parts except for a bottom plate 31, which will be described later, are almost the same as the plan view of the semiconductor module shown in FIG. 4, and will be referred to for convenience. Furthermore, since this semiconductor module is made by connecting two press-contact type semiconductor elements in series, in the following explanation, corresponding parts of the two elements will be denoted by the same numerals, and the suffixes a and b will be used.
Distinguish between elements. In FIG. 4, an insulating plate 32 is placed on a bottom plate 31 of a container 47. The two transistor composite pellets 33a, 33b are placed on the insulating plate 32, sandwiched between collectors M N 34a, 34b, emitter disks 36a 136b, and emitter electrodes 35a, 35b, respectively. The two spring structures 44a and 44b are insulators 37a and 37, respectively.
b, disc springs 38a, 38b and fixing metal plate 39a
, 39b, etc.

As shown in Figure 2, there are two bolts 40 each.
a and 40b (not shown) are screwed into the threaded portion of the bottom plate, the spring structures 44a and 44b connect the transistor complex bellets 33a and 331) and the collector electrode 34.
a, 34b, etc. are pressed against each other.

In this semiconductor module, each transistor complex and the electrode are connected by pressure, so there is no local concentration of large current as in the case of bonding or solder connection structures, and the current flows throughout the entire pressure welding area. flow, and the problems of the first conventional example have been almost eliminated.

(Problems to be Solved by the Invention) In the second latest conventional example, the transistor composite 33
The collector electrode 34 and the like that sandwich it are connected under pressure by a spring structure, but it is important that the connection between these members be uniformly pressed.

In order to achieve uniform pressure contact, the ideal method is to use a press machine and press jig that have parallelism and flatness, and apply equal pressure over the entire contact surface at the same time. However, in the conventional semiconductor device, as shown in FIG. 2, the transistor complex 33a and the like are pressurized while alternately tightening the two bolts 40a, so unlike the ideal method, the uniformity of the pressure-welded state is insufficient. It is.

In particular, due to clumsy pressurization work, etc., the container bottom plate 31 etc.
/υ or distortion may occur. In such a case, the contact resistance of the press-contact surfaces varies depending on the location, and a large amount of current flows in the strongly press-contacted portion, increasing the voltage drop of the press-contact portion. This causes a decrease in the current amplification factor hFE of the transistor and an increase in the saturation snow pressure between the collector and emitter in the on state, and in the case of a thyristor, the forward voltage W
3 or less, and may eventually destroy the device due to local current concentration.

The purpose of the present invention is to maintain the good points of conventional semiconductor devices,
High-quality, high-yield press-contact type semiconductor devices (modules) that eliminate deformation of containers, etc. and always provide uniform press-contact conditions.
The goal is to provide the following.

[Structure of the Invention J Means for Solving the Problems] The present invention provides a structure in which a press-contact type semiconductor element structure placed on the metal base of a container with an insulator interposed therebetween is connected to a current connection terminal. In a semiconductor device that is brought into pressure contact with a current conducting member such as Chrysanthemum by a spring structure, a metal plate having a hardness not smaller than that of a molybdenum plate, such as a hard heat-resistant material such as molybdenum or tungsten, is placed inside the metal bottom plate. This is a semiconductor device characterized by having a metal plate with good conductivity embedded therein.

(Function) By embedding a hard metal with good thermal conductivity, such as a molybdenum plate or a tungsten plate, in the metal bottom plate of a conventional container, it is possible to suppress distortion and deformation of the container due to spring pressure, etc. Deformation of other members being pressed is also prevented, and a uniform pressure contact state can always be obtained.

(Example) Examples of the semiconductor device of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a fragmented sectional view of this semiconductor device, and FIG. 2 is a plan view thereof.

The bottom of the container 52 is a metal bottom plate in which a molybdenum plate 50 is embedded in a metal plate 51 that is a thermally good conductor, such as a bottom plate 51 made of die-cast aluminum. The insulating plate 32 is a ceramic plate. Two semiconductor element structures 33a, 33
b is the main transistor, feedback diode, etc.
They are formed on two semiconductor substrates, and are hereinafter referred to as transistor composites 33a and 33b, respectively. The collector electrodes 34a, 34b and the emitter electrodes 35a, 35b are flat plates made of a copper-based material, and from a part of their periphery there is one 10-long band-shaped current connection terminal bent upward perpendicular to the pressurizing surface. Or two are formed.

That is, the collector electrode 34a is connected to the external current connection terminal 34at.
, the collector electrode 34b has two external and internal current connection terminals 34 bt and 34 btl. Further, the emitter electrode 35a has an internal current connection terminal 35at1, and the emitter electrode 35b has an external current connection terminal 35bt. A base lead, an insulating guide, and a spring are attached to each emitter 136a136b, and the spring allows contact between the base electrode of the transistor complex and the base lead.

Collector electrodes 34a, 34b, emitter board 36a
.

36b and emitter electrodes 35a and 35b constitute current conducting members 43a and 43b, respectively.

The insulators 37a, 37b, disc springs 38a, 38b, and fixing metal plates 39a, 39b are electrically insulated from each other, and are capable of withstanding pressure. The fixing metal plate 39 is used to press and fix the transistor composite 33 and a current conducting member 43 such as electrodes sandwiching the same with two bolts 40 at both ends thereof. Further, drive circuit elements 45a and 45b (not shown) such as a drive transistor and a speed-up diode are attached to the collector electrodes 34a and 34b by soldering and bonding, separately from the main transistor which is pressed into contact with the spring structure. It is being

When assembling this semiconductor module, the various members are placed in a predetermined order and position. At this time, the internal current connection terminals 35at1 and 34btl are disposed at positions facing each other in a vertically slidable manner. The two transistor complexes 33a and 33b are then separately brought into pressure contact with the respective current conducting members 43a and 43b by screwing bolts 40a and 40b into the threads of the metal base plate 31. In this state, tighten the bolt 42 to integrate the internal current connection terminal.

The unit with the circuit configuration thus formed is protected with a gel material, a lid body 46 made of epoxy resin is placed over the metal container 52, and the gap between the metal container 52 and the epoxy lid body 46 is filled with an epoxy resin whose thermal expansion coefficient is close to that of aluminum. Fill with glue.
Also, the spaces between the external current connection terminals 34at, 34bt, 35bt and other connection terminals such as the hihe-sleet and the epoxy lid are filled and sealed with an epoxy adhesive having a coefficient of thermal expansion close to that of copper.

Next, nitrogen is filled in from a tube provided in a part of the epoxy lid 46.

The metal plate embedded in the metal bottom plate needs to be hard enough to not bend or distort due to spring pressure, and since it also serves as a heat sink in most cases, it needs to have as high a thermal conductivity as possible. .

The standard hardness of molybdenum plates is Vickers hardness 160)
-+V (Metal Data Book, edited by the Japan Institute of Metals, p. 147), but there are slight variations due to slight impurities contained, immediately after application, heat treatment, etc. In consideration of industrial conditions such as hardness, thermal conductivity, workability, and availability, the metal plate is preferably a molybdenum plate or a tungsten plate.

In the Moe-Honmiura example, a molybdenum plate with a thickness of 2 to 5 III m was embedded in the bottom plate, making it possible to prevent excessive deformation and distortion.

In the above embodiments, a module consisting of two transistor composites was explained, but the present invention is applicable to a module consisting of one or more transistor composites, or even if a thyristor element is used instead of a transistor element. Applicable to The respective components of the current conducting member and the spring structure are not limited to the present embodiment.

[Effect 1 of the invention] In the semiconductor device of the present invention, by embedding a hard metal plate with good thermal conductivity, such as a molybdenum plate, in the metal bottom plate of the container, deformation and distortion of the metal bottom plate due to spring pressure welding is eliminated, and the semiconductor element And the electrodes are always evenly pressed against each other. The main current flows with uniform density over the entire pressure contact surface of the electrode.

This prevents an increase in the forward voltage drop of the thyristor due to localized large current concentration, which was sometimes seen in conventional semiconductor devices, or an increase in the saturation voltage between the collector and emitter and emitter and base of the transistor, resulting in stable high quality. 19 high-yield semiconductor devices have become available.

[Brief explanation of drawings]

FIG. 1 is a partially fragmented sectional view of a semiconductor device according to the present invention, FIG. 2 is a plan view of the semiconductor device of FIG. 1, FIG. 3 is a sectional view of a conventional semiconductor device, and FIG. 4 is a latest one. FIG. 2 is a cross-sectional view of a conventional semiconductor device. 32... Electrical insulating plate, 33a, 33b... Semiconductor element structure (]/Landisk complex), 34at. 34 bt, 35 at, 35 bt=--current connection terminal, 43a, 43b... current conduction member, 44a
. 44b...Spring structure, 50...Embedded gold fKN
(molybdenum plate), 51...metal bottom plate, 52...
·container. Figure 1 Figure 2 Palace 31'21

Claims (1)

[Scope of Claims] 1. The bottom of the container is made of a metal plate, and a press-contact type semiconductor element structure is placed on the metal bottom plate with an electrically insulating plate interposed therebetween, and a current conducting member having a current connection terminal; A semiconductor device which is brought into pressure contact by a spring structure, characterized in that the metal bottom plate has a metal plate embedded therein having a hardness not smaller than the hardness of the molybdenum plate. 2. The semiconductor device according to claim 1, wherein the metal plate to be embedded is a molybdenum plate or a tungsten plate. 3. Claim 1, wherein a plurality of combinations of the press contact type semiconductor element structure, the conductive member, and the spring structure are provided.
The semiconductor device according to item 1 or 2.